June 5 (UPI) -- Flavored e-cigarettes may help adults quit smoking, but they may make teenagers more inclined to start, a study published Friday by JAMA Network Open found.
The analysis revealed that adults who moved to vaping with non-tobacco-flavored products after smoking traditional cigarettes were 34 percent more likely to quit than those who didn't make the change, the authors said.
But teenagers who vaped non-tobacco-flavored products were nearly seven times more likely to start smoking regularly than those who didn't vape, researchers found.
"Adult smokers who took up vaping non-tobacco-flavored e-cigarettes were more likely to quit smoking than those who took up tobacco-flavored e-cigarettes," study co-author Abigail S. Friedman, assistant professor of health policy and management at the Yale School of Public Health, told UPI.
"The same was not true for youth smoking initiation," Friedman said.
A second study published Friday in the same publication found that users of "electronic nicotine delivery systems" -- including e-cigarettes and vape pens -- are 63 percent more likely to restart smoking than those who choose other smoking cessation aids.
Some 34 million American adults use tobacco products, down from roughly 45 million in the early 2000s, according to the U.S. Centers for Disease Control and Prevention.
About 2 percent of all adult smokers use e-cigarettes, the U.S. Surgeon General's office estimates. The products are popular with teens, with research indicating that as many as 1 in 4 high-schoolers use them.
Friedman and her team analyzed data on 18,000 teens and adults who participated in the Population Assessment of Tobacco and Health Study between 2013 and 2018.
Participants between ages 18 and 24 who vaped non-tobacco-flavored products were more than three times more likely to smoke regularly as they aged than those who didn't, researchers said.
"Our findings are consistent with the claim that non-tobacco-flavored e-cigarettes are more strongly associated with adult smoking cessation than tobacco-flavored e-cigarettes," Friedman said.
The relapse study, conducted by researchers at the National Institutes of Health, found that long-term former smokers who used ENDS were nearly four times more likely to relapse and return to smoking tobacco products.
The findings were based on information from nearly 2,300 adult former smokers also enrolled in the PATH study.
"This study found that the use of ENDS and other tobacco products is associated with increased risk of cigarette smoking relapse among recent former and long-term former smokers who were free of tobacco product use," the NIH authors wrote.
"Decreased time since quitting cigarettes increased the risk of cigarette smoking relapse," they added.
"These studies add to other evidence suggesting that e-cigarettes will not be the final answer to the smoking pandemic that has taken so many lives and that remains a major threat to public health," researchers at the University of Wisconsin wrote in a commentary accompanying the two studies. "However, e-cigarettes could, along with other strategies, play a role in the effort to mitigate the harms of smoking."